Thursday, December 1, is World AIDS Day, an opportunity to remember those lost to the epidemic and to focus on the continuing challenges of universal HIV prevention and treatment. According to a new report from UNAIDS, approximately 37 million people are living with HIV worldwide -- of whom more than 18 million are receiving antiretroviral therapy -- and there were about 2 million new infections in 2015.

Use of syringe exchange and distribution services has increased substantially over the past decade, and HIV diagnoses among people who inject drugs have fallen by nearly half, but just a quarter of drug injectors use only sterile needles and a third reported sharing a needle within the past year, according to the latest Vital Signs report from the Centers for Disease Control and Prevention.